Metering devices of this type are known, for example, from DE 10 2004 011 726 A1. They permit the dispensing of a medium in a mist-like form. For dispensing purposes, the medium is brought from the media reservoir into the metering chamber and, as a result of the high-frequency changes in volume generated by means of the vibration mechanism, emerges from said metering chamber through the metering openings. This form of media discharge may be advantageous both for pharmaceutical and for cosmetic substances.
Disadvantages of the metering devices known from the prior art include the complex design, the discharge of medium through the metering openings not always being reliable and constant, and the inadvertent escape of medium before the device is put into operation.